Design of Outfit Elements in Ships for Fatigue Technical ... - EWF

Reprinting and copying, even in the form of excerpts, only with the consent of the publisher
Bearbeiter: Osenberg
File: D:\Eigene Dateien\Kunden\DVS\Ri+Me\3501\e3501.fm
Erstellt am: 26.08.2004
Zuletzt geändert am: 28.08.2004
DVS – DEUTSCHER VERBAND
FÜR SCHWEISSEN UND
VERWANDTE VERFAHREN E.V.
Preface
At the suggestion of Working Group AG A 6.2 “Damages in welded
Ship Structures” in the DVS – Deutscher Verband für Schweißen
und verwandte Verfahren e.V. the Technical Bulletin “Design
of Outfit Elements in Ships for Fatigue” has been worked
out.
The Technical Bulletin is based on the results of the research
project “Beanspruchungsgerechte Gestaltung von Ausrüstungselementen
an der tragenden Schiffskonstruktion (Design for
Strength of Outfit Elements at the Load-carrying Ship Structure)”
(Author: Dr.-Ing. J. Roerup, Head of Dept.: Prof. Dr.-Ing. H.
Petershagen). The project was conducted at the Technical University
Hamburg-Harburg and was financially supported by the
Arbeitsgemeinschaft industrieller Forschungsvereinigungen “Otto
von Guericke” e.V. (AIF). For details reference is made to the
Research Report No. 295/2001 of the Center of Maritime Technologies
(CMT), Hamburg.
The Working Group wishes to make this Technical Bulletin available
to the shipyards as an aid in the design and arrangement of
outfit elements in load-carrying ship structures. The Working
Group is interested in receiving feedback from its application together
with suggestions for its improvement, which may be considered
and incorporated in subsequent versions.
Germanischer Lloyd (GL) has contributed to this work by advising
and will, as far as applicable, use this Technical Bulletin in the
assessment of structures presented for approval. GL, however,
reserves the right of decisions deviating from its contents in individual
cases.
This publication has been prepared by a group of experts in honorary
co-operation and is recommended for consideration as an
important source for information. The user must always check to
what extent its contents are applicable to his particular case and
whether the version in hand is still valid. Responsibility cannot be
accepted, neither by DVS nor by those having participated in the
preparation of the Technical Bulletin.
Catalogue of Details in Outfit Design
With this catalogue data for the fatigue assessment of outfit design
elements made of steel are provided for practical application.
In the preparation of the catalogue the results of the project
“Beanspruchungsgerechte Gestaltung von Ausrüstungselementen
an der tragenden Schiffskonstruktion (Design for Strength of
Outfit Elements at the load-carrying Ship Structure)” as well as
data from other sources are used. The catalogue is arranged with
a view to an extension by additional elements in the future.
Design of Outfit Elements
in Ships for Fatigue
The catalogue has been worked out in close co-operation with
Germanischer Lloyd (GL) and is based on the Rules of GL. For
further interest it will be decided at a later date whether Rules of
other Classification Societies will be considered.
The fatigue assessment corresponds in actual individual cases to
that according to GL-Rules Issue 2003 (Rules for Classification
and Construction, I-Ship Technology, Part 1 - Seagoing Ships,
Chapter1 - Hull Structures, Section 20 - Fatigue Strength). Accordingly
it must be proven that ∆σmax ≤ ∆σp. In this ∆σmax is the
largest stress range expected during the service life and ∆σp the
permissible stress range. ∆σp is obtained by multiplying the detail
category with a number of coefficients taking stress spectrum,
mean stress, material, weld shape (postweld treatment) and
significance of the structural part into consideration. Details are
given in the GL-Rules mentioned above.
It is further assumed that the welds between outfit elements and
structural members meet the quality requirements for load-carrying
ship structures (see e. g. the GL-Rules mentioned above).
The calculation of maximum permissible stresses in ship hulls is
not explained in detail in this document. It is assumed that
respective data are available to the user. As these data will be
determined by means of structural design software in most
cases, this document is based on the widely spread program system
POSEIDON as an example.
With the application of the programme system POSEIDON the
assessment is simplified to ∆σRperm ≤ ∆σR in way of longitudinal
structures. The lowest permissible detail category ∆σRperm with
regard to the expected service load is then determined within the
program. The user then can find by means of the detail category
the permissible outfit details for the area of the load-carrying ship
structure in question from the catalogue without any further
calculation. Fig. 1 shows a record with lowest permissible detail
categories for the plate panels in way of a midship section. Because
of the higher-tensile steel applied and corresponding higher
permissible stresses in the strength deck outfit details with
detail categories below ∆σR = 50 are not allowed in this area. In
certain areas such as hatch coamings even higher detail categories
are necessary with regard to the existing stress level. In addition
to the ∆σRperm for plate panels POSEIDON also determines
the respective value for longitudinal stiffeners. It must be noted
that at present only stresses due to vertical and horizontal hull
bending and local bending of plates and stiffeners are considered
in POSEIDON. Other possible stress components, e.g. by bending
of grillage structures are not taken into account. If such additional
components are not considered in a separate calculation, it
is recommended for the time being to increase the lowest permissible
detail category ∆σRperm by one category. The format of the
detail catalogue corresponds largely to the catalogue of notch
cases in the GL-Rules, issue 2003. The arrangement follows a
selection of frequently used elements of outfit.
This publication has been drawn up by a group of experienced experts in cooperative work on an honorary basis and it is recommended to pay attention to it as an
important source of knowledge. The user must always check to what extent the contents can be applied to his/her special case and whether the version in his/her
possession is still valid. Any liability on the part of the DVS and those people who have been involved in the elaboration work is excluded.
DVS, Technical Committee, Working Group ″Welding in Shipbuilding and Marine Engineering″
Orders to: DVS-Verlag GmbH, P. O. Box 10 19 65, 40010 Düsseldorf, Germany, Tel.: + 49(0)211/1591- 0, Fax: + 49(0)211/1591-150
November 2004
Technical Bulletin
DVS 3501

Page 2 of DVS 3501
Comments
Description of Type of connection Detail
category
∆σR Equipment Detail Sketch of connection with
fatigue crack and stress
considered σ
Stress concentrations caused by the
opening to be considered as follows
140
(m0 = 4)
Plate edges punched or machine-cut by means of a thermal
cutting process. The cutting surface is free of cracks and
notches. Cutting edges are chamfered or rounded
1.1 Openings uniaxially loaded
∆σmax = K1 ⋅ ∆σN bzw. ∆σRperm ≤ ∆σR /K t
K t: Notch factor according to GL Section 3
∆σN: Nominal stress range related to net
section
alternatively direct determination of ∆σmax from FE-calculation, especially in case of
multiple arrangement of openings
Plate edges which are not meeting the above mentioned
requirements, but are free from cracks and sharp notches
125
(m0 = 3.5)
Machine cut or punched:
or σ x >> σ y
100
(m0 = 3.5)
Manually cut:
Stress concentrations caused by the
opening to be considered as follows
140
(m0 = 4)
Plate edges punched or machine-cut by means of a thermal
cutting process. The cutting surface is free of cracks and
notches. Cutting edges are chamferred or rounded
1.2 Openings biaxially loaded
∆σmax = K1 ⋅ ∆σN K t: Notch factor according to Fig. 2
∆σN : Nominal stress range related to net
section
alternatively direct determination of ∆σmax from FE-calculation, especially in case of
multiple arrangement of openings
Plate edges which are not meeting the above mentioned
requirements, but are free from cracks and sharp notches
125
(m0 = 3.5)
Machine cut or punched:
100
(m0 = 3.5)
Manually cut:
σ x ≈ σ y
Stress concentrations caused by the
opening to be considered as follows
140
(m0 = 4)
1.3 Openings shear-loaded Plate edges punched or machine-cut by means of a thermal
cutting process. The cutting surface is free of cracks and
notches. Cutting edges are chamferred or rounded
∆σmax = K1 ⋅ ∆σN K t: Notch factor according to Fig. 3
∆σN : Nominal stress range related to net
section
alternatively direct determination of ∆σmax from FE-calculation, especially in case of
multiple arrangement of openings
Plate edges which are not meeting the above mentioned
requirements, but are free from cracks and sharp notches
125
(m0 = 3.5)
Machine cut or punched:
100
(m0 = 3.5)
Manually cut:

Comments
Description of Type of connection Detail
category
∆σR Equipment Detail Sketch of connection with
fatigue crack and stress
considered σ
71
63
1.4 Pipe penetration Pipe penetrating a plate with circumferential fillet weld
d ≤ 50 mm
d > 50 mm
Note:
In case of large diameters an assessment based on local
stresses is recommended
Assessment corresponding to doubling
plate
63
56
50
1.5 Drain plugs Drain plugs according to DIN 87721-1
(Diameter about 190 mm)
tD ≤ 0.8 t
0.8 t < tD ≤ 1.5 t
tD > 1.5 t
For t2 ≤ 0.7 ⋅ t1 ∆σR can be upgraded by
one category, however not beyond 80
80
71
63
56
Stiffener welded to a plate in loading direction
R ≤ 50 mm
50 mm < R ≤ 150 mm
150 mm < R ≤ 300 mm
R > 300 mm
2.1 Holder in unsupported plate
panel
arranged parallel to main load
80
Stiffener welded to a plate transversely to load direction
(valid for short and long stiffeners)
2.2 Holder in unsupported plate
panel
arranged transverse to main load
Page 3 of DVS 3501

Page 4 of DVS 3501
Comments
Description of Type of connection Detail
category
∆σR Equipment Detail Sketch of connection with
fatigue crack and stress
considered σ
Fillet weld to plate panel loaded in bending Assessment in individual cases by means
of hot spot stress concept with
∆σSR = 90
2.3 Holder in unsupported plate
panel with or without doubling
plate
Application of a doubling plate can be necessary depending on the local stiffness resulting from the dimensions of plate panel, holder and doubling
plate and from the position of the holder within the plate panel.
Example: Holder 60 mm × 15 mm, position of the holder in the center of the plate panel
Permissible acceleration forces F 2 in [N] for 1 m lever arm, (F 1 = 0)
Location of crack initiation
Plate panel 1800 mm × 600 mm with t
=
10 mm 15 mm 20 mm
Variant
without doubler 1090 N 2680 N 5340 N plate to holder
1940 N 4400 N 8000 N plate to doubler (1)
2000 N 2120 N 2150 N doubler to holder (2)
with doubler
∅ = 100 mm
t = 10 mm
While the permissible force for a 10 mm thick plate panel is increased by a factor of about 2 if a doubling is fitted, the permissible force for a 20 mm
thick plate panel is by a factor of about 2,5 higher for the holder without doubling plate.
incomplete circumferential weld may be
applied in dry spaces only.
Unloaded overlapped plate fillet welded to longitudinally
loaded structural member
2.4 Holder at stiffener
Alternative 1
For R > 150 mm ∆σR to be downgraded
by one category, for R 50 mm ≤ ∆σR can
be upgraded by one category
56
50
– at bulb flat profile or flat bar
– at angle bar
For structural members loaded by
bending ∆σR to be downgraded by one
category
For t2 ≤ 0.7 ⋅ t1 ∆σR can be upgraded by
one category, however not beyond 56.
Plate welded to an edge of a plate or girder flange
R ≤ 50 mm
50 mm < R ≤ 150 mm
150 mm < R ≤ 300 mm
R > 300 mm
2.5 Holder at stiffener
Alternative 2
For plates or girder flanges loaded in inplane
bending ∆σR to be downgraded by
one category
56
50
45
40

Comments
Description of Type of connection Detail
category
∆σR Equipment Detail Sketch of connection with
fatigue crack and stress
considered σ
Holder to be arranged in neutral axis of
stiffener if possible
Stiffener welded to a plate in load direction
R ≤ 50 mm
50 mm < R ≤ 150 mm
150 mm < R ≤ 300 mm
R > 300 mm
2.6 Holder at stiffener
Alternative 3
For t2 ≤ 0.7 ⋅ t1 ∆σR can be upgraded by
one category, however not beyond 80
80
71
63
56
80 The detail category is also valid for not
fully circumferential welded holders (see
2.4).
Fillet-welded stiffener transverse to loading direction (valid
for short and long stiffeners)
2.7 Holder at stiffener
Alternative 4
For stiffeners loaded in bending ∆σR to be
downgraded by one category.
In way of the rounded corner of an opening
with the radius r a minimum distance x
from the edge to be kept (hatched area):
2.8 Holder at cut-out or opening Holder welded in way of an opening and arranged parallel
to the edge of the opening.
x [mm] = 15 + 0.175 ⋅ r [mm]
100 mm ≤ r ≤ 400 mm
In case of an elliptical rounding the mean
value of both semi-axes to be applied
R ≤ 150 mm
not valid for hatch corners
Circular doubler plate with max. 150 mm diameter.
tD ≤ 0.8 t
2.9 Doubler plate for holder in
unsupported plate panel
Page 5 of DVS 3501
71
63
56
0.8 t < tD ≤ 1.5 t
tD > 1.5 t

Page 6 of DVS 3501
Comments
Description of Type of connection Detail
category
∆σR Equipment Detail Sketch of connection with
fatigue crack and stress
considered σ
For t2 ≤ 0.7 ⋅ t1 ∆σR can be upgraded by
one category, however not beyond 80
80
71
Stiffener welded to a plate in loading direction
R ≤ 50 mm
50 mm < R ≤ 150 mm
3.1 Rail stanchions
arranged parallel to the main
loading direction
80
Stiffener welded to a plate transverse to the loading
direction
3.2 Rail stanchions
arranged transverse to the main
loading direction
80 The sketch shows the connection of a
bollard to a deck. The main stress is
approximately directed perpendicular
towards the bollard wall for all angles
3.3 Bollard Fillet-welded stiffener transverse to the loading direction
(valid for short and long stiffeners)
For t2 ≤ 0.7 ⋅ t1 ∆σR can be upgraded by
one category.
56
50
Stiffener welded to a plate in loading direction
150 mm < R ≤ 300 mm
R > 300 mm
4.1 Foundations
Ends of girders parallel to main
loading direction
80
Fillet-welded stiffener transverse to the loading direction
(valid for short and long stiffeners)
4.2 Foundations
For girders tranverse to main
loading direction

Comments
Description of Type of connection Detail
category
∆σR Equipment Detail Sketch of connection with
fatigue crack and stress
considered σ
For t2 ≤ 0.7 ⋅ t1 ∆σR can be upgraded by
one category.
Stiffener welded to a plate in loading direction
R > 300 mm 56
Assessment of the opening edges by
means of a direct determination of the
notch factor only
4.3 Small hatches
Assessment of weld at transition
from deck to coaming in a hatch
corner
For t2 ≤ 0.7 ⋅ t1 ∆σR can be upgraded by
one category.
71
63
56
Stiffener welded to a plate in loading direction
R ≤ 150 mm
150 mm < R ≤ 300 mm
R > 300 mm
4.4 Container foundations
Assessment of girder end parallel to
main loading direction
∆σR may be upgraded by one category:
– reinforced end weld
– weld angle ≤ 30°
– connection length ≤ 150 mm
End of a long doubler at the flange of a girder
tD ≤ 0.8 t
56
50
45
0.8 t < tD ≤ 1.5 t
tD > 1.5 t
5.1 Hatch cover bearings (pads)
Assessment with regard to loading
of ship structure
Load-carrying fillet weld Assessment in individual cases by means
of hot-spot concept with ∆σSR = 90
5.2 Hatch cover bearings (pads)
Assessment with regard to
container loads
Page 7 of DVS 3501

Page 8 of DVS 3501
Comments
Description of Type of connection Detail
category
∆σR Equipment Detail Sketch of connection with
fatigue crack and stress
considered σ
Required throat thickness "a" of fillet
welds related to weld penetration depth
"e"
80
Stiffener arranged transverse to main loading direction
σ2 ≤ 0.4 σ1 Assessment to be based on σ 1 only
5.3 Hatch cover locking device
Arranged transverse to main
loading direction
αmin 0.82 t 1 2.8 e ⎛ –
⎝
-- ⎞
t ⎠
0.74
=
⋅ ⋅
t: Thickness of locking device. Otherwise
assessment as cruciform joint
Assessment with regard to biaxial load
Assessment to be based on σ2 only
Biaxially loaded fillet welded cruciform joint, failure from the
weld root.
(reference stress to be determined for the weld section) 30
Assessment of unsupported hatch cover
guide corner see 4.4.
71
63
5.4 Hatch cover guide Detail welded to girder flange, bulb or plate with soft
transition (tapered end or radius); c ≤ 2 t2, max. 25 mm
r ≥ 0.5 h
r < 0.5 h or ϕ ≤ 20°
ϕ > 20° as stiffener in load direction
For t2 ≤ 0.5 t1 ∆σR may be increased by one category.

Figure 1. Lowest permissible detail categories in the midship section of a container vessel.
Kt
12
10
8
6
4
2
0
l/a=2
l/a=4
l/a=1
0 0.1 0.2 0.3 0.4 0.5
r/a
Figure 2. Notch factors K t for rounded rectangular openings under biaxial load.
a
σy
l
r
σx = σy
σx
Page 9 of DVS 3501

Page 10 of DVS 3501
Kt
18
16
14
12
10
8
6
4
2
0
l/a=2
l/a=4
l/a=1
0 0.1 0.2 0.3 0.4 0.5
r/a
Figure 3. Notch factors K t for rounded rectangular openings under shear load.
Publications, Normative References
Research Report No. 295/2001 Center of Maritime Technologies (CMT), Hamburg
GL-Rules Issue 2003 Germanischer Lloyd, Hamburg
DIN 87721-1 Ablassverschraubungen – Teil 1: Zusammenstellung, Einbau
a
l
r